This invention relates to reamers and similar tools for enlarging bore holes and, in particular, to blockless reamers.
Reamers for enlarging bore holes drilled for oil wells and mine shafts have been known in the drilling art for many decades. Typically, a reamer includes a central body having three or more roller reamer units mounted at circumferally spaced intervals around the tool body. The reamer tool is mounted in a string of drill pipe, drill collar or other rotatable pipe such that the reamer is rotated with the drill pipe through the well bore in order to enlarge the bore. The roller reamer units rollably engage the well bore wall to enlarge the bore as the drill string moves through the hole. Roller reamers are used to roll against the hole wall of an in-gauge hole to reduce the torque of the drill collars against the hole wall of a directionally drilled hole.
Roller reamer tools have traditionally included means for installing a reamer unit whereby the reamer unit was sealed into the reamer tool. Blocks have been utilized to fixedly hold a reamer unit in position whereby the shaft of a reamer unit extends into upper and lower bearing blocks so as to be fixedly mounted within a pocket cut into a reamer tool. The blocks are machined to cooperate with the pocket to hold the reamer unit in place within a pocket. The reamer tool pocket must also be machined to specifically allow the block piece to be fixedly fitted therein. Blocks of a variety of shapes and sizes have been applied in the prior art.
Blocks mounted in pockets cut into the reamer tool can be cumbersome to insert and remove causing the reamer unit to be difficult to remove from the reamer tool. The inclusion of blocks into the design of the reamer tool requires that individual blocks and a specific tool pocket shaped to receive an individual block must be machined specifically to fit together.